The U.S. Food and Drug Administration sent a letter to healthcare providers warning them of safety risks associated with using surgical staplers and staples after an "increasing number of adverse events," including the continued reporting of deaths and serious injuries.

The agency issued a letter to healthcare providers March 8, saying that between Jan. 1, 2011 and March 31, 2018, the FDA received more than 32,000 individual reports of device malfunction, 9,000 reports of serious injuries and 366 reports of deaths.

Malfunctions include staplers misfiring during surgery, not firing at all mid-procedure, or firing the wrong type of staple, according to the FDA.

In the letter, the FDA provided a list of instructions on how best to use the surgical staplers and said it will hold a public comment period and a hearing regarding the safety of the medical devices in the near future, but did not give specific dates.

The FDA said it may reclassify surgical staplers and staples as class II medical devices, which would require stricter oversight of products before and after they go to market.

The letter was sent one day after Kaiser Health News published an investigative article about the FDA's medical device reporting program. According to the article, the FDA allowed certain companies to report malfunctions and injuries through an "alternative summary reporting" system. This system housed millions of reports that were kept in an obscure, internal system.

Medical device experts and even a former FDA commissioner were not aware that the system existed, according to Kaiser Health News.

While deaths are recorded in the FDA's public database manufacturer and user facility device experience, the article said serious injuries were reported through this alternate system for more than 100 medical devices, including surgical staplers and staples.

The FDA did include a link to the alternative summary report system in the March 8 letter.

The safety of medical devices has become a controversial issue for the FDA. Netflix Inc.'s documentary "The Bleeding Edge" criticized the agency's medical device approval process, saying the FDA knowingly allowed dangerous devices to go to market. The documentary specifically highlights Bayer AG's permanent birth control device Essure, which users claim has caused permanent injuries.

Bayer has defended the safety of the product, but said in 2018 it was pulling the device from U.S. markets due to poor sales.